Inherited Peripheral Neuropathies (IPN) form a clinically diverse group of disorders affecting 1 in 2500 individuals1. The most common type is Charcot-Marie-Tooth disease (CMT), a sensorimotor neuropathy causing progressive distal muscle atrophy, weakness and sensory loss. Autosomal dominant, autosomal recessive (AR) and X-linked forms of IPN are representing a genetic spectrum of at least 50 causal genes. Even after subdivision in specific phenotypes, IPN are genetically heterogeneous. Although striking clinical features may be of particular use to distinguish genetic subtypes and guide diagnostic screening, many families remain without molecular diagnosis suggesting the existence of unknown causes. Our understanding of these disorders has progressed from the description of the clinical phenotypes and delineation of the electrophysiological and pathological features to the identification of disease genes and elucidation of the underlying molecular mechanisms. Recent molecular analysis of the inherited peripheral neuropathies (IPN) has led to important insights into the process of myelination and the function of some of the genes involved. An important problem for the physician is that the IPN show considerable clinical and genetic heterogeneity. The discovery that mutations in multiple genes result in similar phenotypes argues for complex protein interactions and complementing functions for each protein product within the nerve tissue. Knowledge of the structure and function of the causal genes is currently being actively pursued to better classify peripheral neuropathies and to elucidate the underlying molecular mechanisms of these diseases. Thus, the knowledge of the exact genetic aberration in the patients has important ramifications for diagnosis, prognosis, genetic counseling, and approaches for therapy.